Lever toggle switch mechanism with lever rotation preventing means



Feb. 15, 1966 w. J. SCHAAD ETAL 3,235,679 LEVER TOGGLE SWITCH MECHANISM WITH LEVER ROTATION PREVENTING MEANS Filed Oct. 18, 1963 2 Sheets-Sheet 1 INVENTORS William J Schema BY Wz'llzam MSG/2021a Feb. 15, 1966 J. SCHAAD ETAL 3,235,679 LEVER TOGG'LE SWITCH MECHANISM WITH LEVER ROTATION PREVENTING MEANS Filed Oct. 18, 1963 2 Sheets-Sheet 2 a 22 44 '1 L 68 115 4 i 4 32 f; L (8 FJGOG a? .90 752 74 .90 fcjx INVENTORS Willg'am J'c'haad BY Willzam NSchznk United States Patent 3,235,679 LEVER TOGGLE SWITCH MECHANISM WITH LEVER ROTATION PREVENTING MEANS William J. Schaad, Winnetka, and William N. Schink,

Crystal Lake, 11]., assignors to Indak Manufacturing Corp., Northbrook, Ill., a corporation of Illinois Filed Oct. 18, 1963, Ser. No. 317,327 15 Claims. (Cl. 200-16) This invention relates to electrical switches and pertains particularly to switches of the type having an operating lever.

One object of the present invention is to provide a new and improved electrical switch having an insulating carriage which is slidable longitudinally in the casing of the switch, and a contactor mounted on the carriage and adapted to be moved therewith into engagement with four or more contacts simultaneously so as to connect all of them together.

A further object is to provide a new and improved switch of the foregoing character in which firm contact is positively assured between the contactor and all of the contacts.

It is a further object to provide a switch of the foregoing character in which the contactor comprises two or more parallel contactor bars and one or more flexible resilient strips connected between the bars so as to provide for relative rocking movement between the bars.

Another object is to provide a new and improved switch having a slidable insulating carriage which is adapted to be moved by a swingable lever, together with means on the carriage for preventing rotation of the lever about its own axis.

Another object is to provide a new and improved switch having a sheet metal housing in which a plurality of side walls are bent rearwardly from a front wall, together with an insulating plate which forms the rear wall of the housing and is provided with a forwardy projecting flange or lip which embraces and retains the sheet metal side walls.

Another object is to provide a new and improved switch having a contactor which is slidable from four insulating bosses or points to four contact points, an air gap being formed between each of the bosses and the corresponding contact point to assist in making and breaking the circuit.

Another object is to provide a new and improved switch in which two springs are positioned between the contactor and an insulating bar, and in which the bar in turn engages the lever which operates the sliding carriage for the contactor, so that the springs bias the contactor rearwardly while also biasing the lever forwardly and taking up any play in the lever.

Further objects and advantages of the present invention will appear from the following description taken with the accompanying drawings in which:

FIGS. 1 and 2 are front and rear perspective views of an electrical switch to be described as an illustrative embodiment of the present invention.

FIG. 3 is an exploded view of the switch with certain portions in section.

FIGS. 4 and 5 are longitudinal sections through the switch, taken generally along the lines 44 and 5-5 in FIG. 6.

FIG. 6 is a transverse section taken the line 66 in FIG. 4.

FIGS. 7 and 8 are front and rear views of the insulating carriage for the switch, taken generally as indicated by the lines 77 and 8-8 in FIG. 3.

FIG. 9- is a perspective view showing the contactor for the switch.

FIG. 10 is a perspective view showing an insulating generally along bar which is interposed between the contactor springs and the operating lever.

FIG. 11 is a rear elevational view of the operating lever.

FIGS. 12 and 13 are diagrammatic elevational views showing the contact plate and the contactor, with the switch in its oil and on positions, respectively.

It will be seen that the drawings illustrate an electrical switch 20 of the type which is operated by a lever 22 projecting forwardly from the front of the switch. As shown, the switch 20 is provided with a casing or housing 24 which is made of sheet metal. In this case, the housing 24 has a front wall 26, two longitudinal side walls 28 and 29, and two transverse side or end walls 30 and 31. The side walls 28-31 are bent rearwardly at right angles from the front wall 26. Thus, the housing 24 is substantially rectangular in shape. The longitudinal walls 28 and 29 have tabs or flanges 34 which are bent at right angles to the longitudinal walls, outside the end walls 30 and 31.

The illustrated switch 20 has a forwardly projecting threaded bushing or mounting sleeve 36 which supports the lever 22. The bushing 26 is formed with a bore 38 in which the lever 22 is movably mounted. In this case, the bushing 36 extends through a central opening 40 in the front wall 26. The bushing 36 has a rear portion 42 which is riveted or flanged to retain the bushing in the opening 40. A reinforcing plate 44 may be clamped between the front wall 26 and a rearwardly facing shoulder 46 on the bushing 36.

The rear side of the housing 24 is closed by an insulating terminal plate 48 which may be made of plastic or other suitable insulating material. As shown, the insulating plate 48 is retained on the housing 24 by a plurality of tabs 50 which are formed on the side walls 2831 and are bent behind the plate 48. Slots 52 may be formed in the plate 48 to receive the tabs 50.

In the illustrated switch 20 a plurality of terminal lugs or prongs 54, 55, 56 and 57 are riveted or otherwise secured to the rear side of the insulating plate 48. It will be noted that the illustrated switch has four such terminal prongs, but the number might be different. The illustrated prongs are in the form of rectangular blades which are adapted to be received by a suitable connector or receptacle, not shown.

In accordance with one of the features of the present invention, the insulating terminal plate 48 is formed with a forwardly projecting flange or lip 60 which extends around the outer edges of the plate and is adapted to embrace and retain the slide walls 28, 29, 30 and 31 of the housing 24. The lip 60 positively prevents the side walls 2831 from spreading at the rear of the housing 24. Moreover, the lip 60 is effective to maintain the rectangular shape of the rear of the housing 24. It will be seen that the lip 60 prevents the side walls 28-31 from being bent outwardly, while the engagement between the tabs 50 and the plate 48 prevent the side walls from being bent inwardly. Thus, the lip 60 insures that the switch will be especially sturdy and that the rectangular shape of the housing will be precisely maintained.

As shown in FIGS. 4 and 5, a ball and socket joint is formed between the lever 22 and the bushing 36 at the front of the housing 24. Thus, a ball shaped portion or formation 64 is provided on an intermediate portion of the lever 22. The ball 64 is swingably received in an annular socket or shoulder 66 in the bushing 36. The lever 22 has a forwardly projecting stem or portion 68 to which a handle 70 is rigidly secured. The lever 22 also has a rearwardly projecting stem or portion 72 inside the housing 24. The bore 38 in the bushing 36 is large enough to permit free swinging movement of the lever 22.

Within the housing 24, the switch 20 is proivded with an insulating carriage 74 which is slidable longitudinally along a straight line. The carriage 74 is generally rectangular in shape and corresponds generally in width and depth to the width and depth of the rectangular cavity or space 76 within the housing 24, so that the carriage is freely slidable along the length of the housing. The illustrated carriage 74 has a pair of rearwardly projecting rails or'runners 80 which are slidable along the insulated 1 plate 48, and a pair of forwardly projecting rails or runners 82, adjacent the front wall 26.

In this case, the lower end of the carriage 74 is engageable with the lower wall 31 of the housing 24, to limit downward movement of the carriage. Upward movement of the carriage is limited by engagement of the upper end of the carriage with a rearwardly projecting shoulder or flange 84 on the insulating plate 48.

The front side of the illustrated carriage 74 is formed with a recess or socket 86 for receiving the rearwardly projecting arm 72 of the lever 22. In accordance with another feature of the present invention, the socket 86 is formed with flat vertical side walls or surfaces 88 which are slidably engageable with flat vertical surfaces 90 on the extreme rear portion of the arm 72. The flat surfaces 88 and 90 prevent the lever 22 from being rotated about its own longitudinal axis, while permitting the normal vertical swinging movement of the lever. Thus, the front end of the lever 22 may be provided with a code letter, number or other symbol, such as the letter P, which is maintained in an upright position, as shown in FIG. 1. The flat surfaces 88 and 90 are parallel to the direction of movement of the carriage 74. It will be seen that the flat surfaces 90 are formed on a spherically curved knob or ball 92 formed on the extreme rear end of the arm 72. The socket 86 has curved upper and lower portions 94 against which the ball 92 is freely rockable. In front of the socket 88 the carriage '74 is formed with an enlarged bore or recess 96 which affords ample clearance for the swinging movement of the arm 72.

Detent means are preferably provided for locating and detaining the carriage 74 in its extreme upper and lower positions. In this case, such detent means comprise a pair of detent balls 98 which are mounted in bores 100 formed in the front corners of the carriage 74. The balls 98 are pressed forwardly by compression springs 102 which are positioned in the bores 100 behind the balls 98. Thus, the balls 98 are pressed against the front wall 26 of the housing 24.

As shown to best advantage in FIGS. 4 and the detent balls 98 are engageable with detent cam formations 104 and 106 which are provided on the inside of the front wall 26. There are two sets of the cams 104 and 106, one for each ball 98. The illustrated cams 104 and 106 take the form of horizontal bars which are struck rearwardly from the front wall 26.

When the switch is in its off position, as shown in FIG. 4, each ball 98 is detained between the upper and lower cams 104 and 106. When the switch is operated to its on position, the carriage 74 moves downwardly, and each ball 98 passes over the lower camming bar 106. It will be understood that the detent elements 98-106 give the switch a definite snap action, so that the carriage 74 moves abruptly between its on and off positions.

The illustrated switch 20 is provided with four contact points 111, 112, 113 and 114 which are mounted on the insulating plate 48. The contacts 111-114 may take the form of rounded heads on rivets 115, 116, 117 and 118. The terminal prongs 54-57 are secured to the rear ends of the rivets 115-118. The contacts 111-114 project forwardly from the insulating plate 48.

It will be seen that the contacts 111-114 are arranged in two parallel vertical rows. Two of the contacts are positioned in each row. Thus, the contacts 111 and 112 are in one row, while the contacts 113 and 114 are in the other row. The upper contacts 111 and 113 are opposite each other at the same horizontal level. This is also true of the lower contacts 112 and 114.

To engage the contacts 111-114 the insulating carriage 74 supports a contactor 120. As shown to good advantage in FIGS. 9, 12 and 13, the contactor is preferably made in one piece of thin resilient spring metal. The illustrated contactor 120 has two bar portions 121 and 122 which are connected together by a thin, flexible, resilient, strip portion 123 extending therebetween at one end of each bar portion.

The illustrated bar portion 121 has rearwardly offset members 126 and 127. Similarly the bar portion 122 has rearwardly offset members 128 and 129. The bar portions 121 and 122 have forwardly offset central portions and 131. The rearwardly offset portions 126- 129 are adapted to engage the respective contacts 111- 114, when the switch is in its on position, as shown in FIG. 13. When the switch is in its off position as shown in FIG. 12 the forwardly offset portions 130 and 131 bridge overthe contacts 111 and 113.

The illustrated contactor 120 has four forwardly projecting prongs 134, 135, 136 and 137 which are adapted to be slidably received in slots or recesses 138, 139, 140 and 141 formed in the rear side of the carriage 74. In this way, the contactor is located and retained on the carriage 74.

Two contactor springs 144 and 145 are provided to press the contactor 120 rearwardly. The springs 144 and 145 are positioned in sockets 146 and 147 formed in the carriage 74. The rear ends of the springs 144 and 145 engage the contactor bars 121 and 122, respectively. Bosses or projections 148 and 149 extend forwardly from the central portions 130 and 131 of the contactor bars 121 and 122 for centering and retaining the springs 144 and 145.

The front ends of the springs 144 and 145 preferably engage the opposite ends of a bar 152 made of insulating material, such as a suitable plastic. The central portion of the bar 152 engages the ball or knob 92 at the rear end of the operating lever 22. In this way the pressure of the springs 144 and 145 biases the lever 22 forwardly so that the ball formation 64 is held snugly against the shoulder or socket 66. Thus, the springs 144 and 145 take up any slack in the lever and prevent it from rattling. A slot 154 is formed between the spring sockets 146 and 147 for receiving the bar 152. The ends of the bar 152 extend into the spring sockets 146 and 147.

When the switch is in its off position, as shown in FIGS. 4 and 12, the rearwardly offset members 126-129 of the contactor 120 are out of engagement with the contacts 111-114. The forwardly offset portions 130 and 131 of the contactor bars bridge over the contacts 111 and 113. To engage the rearwardly offset contactor members 126- 129 when the switch is in its off position, the insulating plate 48 is formed with four forwardly projecting insulating points or bosses 161, 162, 163 and 164 which are located above the corresponding contacts 111-114. As shown, the insulating bosses 161-164 are oval in shape, although they may be of some other shape. When the switch is operated between its two positions, the contactor members 126-129 ride smoothly between the contacts 111-114 and the insulating bosses 161-164. Thus, the insulating bosses cause the switch to operate smoothly and minimize or eliminate false detenting action due to the engagement of the contactor with the contacts. Moreover, the insulating bosses 161-164 are spaced from the corresponding contacts 111-114 so that an air gap 166 is provided between each contact and the corresponding insulating boss. When the contactor moves out of engagement with the contacts 111-114, any resulting arcs are drawn across these air gaps 166, so that the arcs do not burn the insulating plate 48. Thus, the insulating bosses 161-164 contribute to the long life of the switch.

When the switch is in its on position, as shown in FIGS. 5 and 13, the contactor 120 engages all four of the contacts 111-114 simultaneously. The construction of the switch insures that a firm and equalized contact pressure will be provided between the respective contacts 111-114 and the contactor members 126-129. The two contactor springs 144 and 145 press the contactor bars 121 and 122 rearwardly so that both bars are pressed firmly against the corresponding contacts. The thin resilient interconnecting strip 123 permits relative rocking movement between the two contactor bars 121 and 122 so that the contact pressure at the offset ends of the contactor bars will be equalized. It will be realized that it is difficult to provide equalized contact pressure between four points on a contactor and four stationary contacts, because of irregularities that may exist in the shape of the contactor or the height of the contacts. However, the resilient interconnecting strip 123 introduces an element of flexibility which obviates any tendency of the contactor to enage the contacts unevenly.

When the switch is off, all the contacts are insulated from one another. When the switch is on, all the contacts areconnected together. A switch of this kind has various applications. Thus, it may be employed in an automobile for energizing all of the front and rear turn signal lights simultaneously from the flasher circuit normally used for flashing the turn signals. The flashing of all of the turn signal lights produces an emergency stop signal which is used when the automobile is stopped on the side of a street or highway. The switch may be employed whenever three normally separate circuits are to be energized simultaneously from a common power circuit. Many of the features of the present switch may be employed in other switches having modified contact and contactor. arrangements. Thus, many of the features of the present switch are applicable to the standard types of switches, such as double-pole double-throw, double-pole single-throw, single-pole double-throw and single-pole single-throw.

Various other modifications, alternative constructions and equivalents may be employed Without departing from the true spirit and scope of the present invention, as exemplified in the foregoing description, and defined in the following claims.

We claim:

1. In an electrical switch, the combination comprising a generally rectangular housing, an insulating carriage slidable longitudinally in said housing, means for moving saidcarriage, an insulating plate constituting one wall of said housing and opposite one side of said carriage, four contacts mounted on said plate opposite said carriage and arranged in two parallel longitudinal rows with two of said contacts in each row, a conductive contactor mounted on said carriage andhaving two parallel contactor bars opposite said rows, said contactor having a flexible transverse connecting strip portion connected between said bars at one end of each bar, the other ends of said bars being free of each other, and spring means mounted between said carriage and said bars and biasing said bars against said plate and said contacts, said contactor bars having offset portions for engaging all four of said contacts simultaneously so as to connect them all together, said strip portion forming the sole connection between said bars and providing for relative rocking movement therebetween to insure firm contact between said bars and all of said contacts.

2. In an electrical switch, the combination comprising a generally rectangular housing, an insulating car-riage slidable longitudinally in said housing, a lever for moving said carriage, said housing having a wall formed with an opening for receiving said lever, said lever having an outer end portion extending through said opening, and an inner end portion engaging said carriage, a ball shaped formation on said lever between said outer and inner end portions, said wall having a socket formation around said opening for rotatably receiving said ball formation, said inner end portion of said lever having a pair of parallel fiat surfaces thereon extending in the direction of movement of said carriage, and means on said carriage forming a recess for receiving said inner endportion of said lever, said recess having a pair of opposite flat surfaces slidably engaging said fiat surfaces on said inner end portion of said lever for preventing rotation of said lever about its own longitudinal axis.

3. In an electrical switch, the combination comprising a housing made of sheet metal and having a front wall and four side walls folded rearwardly from said front Wall, a contact plate made of insulating material and mounted against the rear edges of said side walls for closing the rear of said housing, said side walls having tabs thereon bent around the rear of said plate for retaining said plate on said housing, said plate having slots therein for receiving said tabs, and a forwardly projecting flange formed integrally with said plate and extending around the edges thereof, said flange embracing and retaining the rear edges of said housing, said rear edges of said sheet metal housing being confined within said flange on said insulating plate.

4. In an electrical switch, the combination comprising a generally rectangular housing, an insulating carriage slidable longitudinally in said housing, a lever for moving said carriage, said housing having a front wall with an opening therein for receiving said lever, said lever having a front portion projecting forwardly through said opening, and a rear portion for engaging said carriage, said carriage having a socket therein for receiving said rear end portion, said socket and said rear end portion having interengaging flat surfaces thereon parallel to the direction of movement of said carriage for preventing rotation of said lever about its own longitudinal axis, an insulating plate constituting the rear wall of said housing, four contacts mounted on said plate opposite the rear side of said carriage and arranged in two parallel longitudinal rows with two of said contacts in each row, a conductive contactor mounted on the rear of said carriage and having two parallel contactor bars opposite said rows of contacts, said contactor having a flexible resilient connecting strip connected between said bars at one end of each bar, spring means mounted on said carriage and biasing said bars against said plate and said contacts, said contactor bars having rearwardly offset portions for engaging all four of said contacts simultaneously so as to connect them all together.

5. In an electrical switch, the combination comprising a generally rectangular housing, an insulating carriage slidable in said housing, a lever for moving said carriage, said housing having a front wall with an opening therein for receiving said lever, said lever having a front portion projecting forwardly through said opening and a rear portion for engaging said carriage, said carriage having an opening therein for receiving said rear portion, an insulating plate constituting the rear wall of said housing, a plurality of contacts mounted on said plate opposite the rear side of said carriage, a conductive contactor mounted on the rear of said carriage and having two parallel contactor bars with a flexible resilient connecting strip extending therebetween at one end of each bar, a pair of springs engaging said bars and pressing said bars rearwardly against said contacts and said insulating plate, and an insulating bar interposed between said springs and said rear portion of said lever whereby said springs press said lever forwardly, said springs engaging the rear side of said insulating bar adjacent the ends thereof, said rear portion of said lever engaging the central portion of the front of said insulating bar.

6. In an electrical switch, the combination comprising a housing, an insulating carriage slidable linearly in said housing, means for moving said carriage, an insulating plate constituting one wall of said housing and opposite one side of said carriage, four contacts mounted on said plate opposite said carriage, a conductive contactor mounted on said carriage and having two contactor bars opposite said contacts, said contactor having a flexible connecting strip portion connected between said bars,

and spring means mounted between said carriage and said bars and biasing said bars against said plate and said contacts, said contactor bars being engageable with all four of said contacts simultaneously so as to connect them all together, said strip portion forming the sole connection between said bars and providing for relative rocking movement therebetween to insure firm contact between said bars and all of said contacts.

7. In an electrical switch, the combination comprising a generally rectangular housing, an insulating carriage slidable in said housing, means for moving said carriage, an insulating plate constituting one wall of said housing and opposite one side of said carriage, four contacts mounted on said plate opposite said carriage and arranged in two parallel longitudinal rows with two of said contacts in each row, said carriage being movable along said rows, a conductive contactor mounted on said carriage and having two parallel contactor bars opposite said rows, said contactor having a flexible transverse connecting strip portion connected between end portions of said bars, and spring means mounted between said carriage and said bars and biasing said bars against said plate and said contacts, said contactor bars having portions for engaging all four of said contacts simultaneously so as to connect them all together, said strip portion forming the sole connection between said bars and providing for relative rocking movement therebetween to insure firm contact between said bars and all of said contacts.

8. In an electrical switch, the combination comprising a generally rectangular housing, an insulating carriage slidable linearly in said housing, means for moving said carriage, an insulating plate constituting one wall of said housing and opposite one side of said carriage, four contacts mounted on said plate opposite said carriage and arranged in two parallel rows with two of said contacts in each row, a conductive contactor mounted on said carriage and having two parallel contactor bars opposite said rows, said contactor having a flexible transverse connecting strip portion connected between said bars adjacent one end of each bar, the other ends of said bars being free of each other, and two springs mounted between said carriage and said bars and biasing said bars against said plate and said contacts, said contactor bars having offset portions for engaging all four of said contacts simultaneously so as to connect them all together, said strip portion forming the sole connection between said bars and providing for relative rocking movement therebetween to insure firm contact between said bars and all of said contacts.

9. In an electrical switch, the combination comprising. a housing, an insulating carriage slidable linearly in said through said opening, and an inner end portion engaging said carriage, said inner end portion of said lever having a flat surface thereon extending in the direction of movement of said carriage, and means on said carriage for receiving said inner end portion of said lever, said means having a fiat surface slidably engaging said flat surface of said lever, said flat surfaces being parallel to the longitudinal axis of said lever for preventing rotation of said lever about its own longitudinal axis.

10. In an electrical switch, the combination comprising a housing, an insulating carriage slidable linearly in said housing, a lever for moving said carriage, said housing having a wall formed with an opening for receiving said lever, said lever having an outer end portion extending through said opening, and an inner end portion engaging said carriage, and slidably interfitting non-circular members on said inner end portion of said lever and on said carriage for preventing rotation of said lever ab ut its o n long udinal axis.

11. In an electrical switch, the combination comprising a housing made of sheet material and having a front wall and side walls folded rearwardly from said front wall, a contact plate made of insulating material and mounted against the rear edges of said side walls for closing the rear of said housing, means for retaining said plate on said housing, and forwardly projecting lip means formed integrally with and extending from the edges of said plate outside the rear edges of said side walls for confining said rear edges.

12. In an electrical switch, the combination comprising a housing having a front wall and side walls extending rearwardly from said front wall, a contact plate made of insulating material and mounted against the rear edges of said side walls for closing the rear of said housing, and forwardly projecting lip means formed integrally with and extending from the edges of said plate outside the rear edges of said side walls for retaining said side walls.

13. In an electrical switch, the combination comprising a housing, an insulating carriage slidable linearly in said housing, a lever for moving said carriage, said housing having a front wall with an opening therein for receiving said lever, said lever having a front portion projecting forwardly through said opening and a rear portion engaging said carriage, said carriage having an opening therein for receiving said rear portion, an insulating plate constituting the rear wall of said housing, a plurality of contacts mounted on said plate opposite the rear side of said carriage, a conductive contactor mounted on the rear of said carriage and having two contactor bars with a flexible resilient connecting strip extending therebetween, a pair of springs engaging said bars and pressing said bars rearwardly against said contacts and said insulating plate, and an insulating member interposed between said springs and said rear portion of said lever whereby said springs press said lever forwardly.

14. The combination of claim 13, in which there are four of said contacts, each of said contactor bars being engageable with two of said contacts to connect all of said contacts together.

15. In an electrical switch, the combination comprising a housing, an insulating carriage slidable linearly in said housing, means for moving said carriage, an insulating support constituting one wall of said housing and opposite one side of said carriage, at least four contacts mounted on said support opposite said carriage, a conductive contactor mounted on said carriage and having .at least two contactor bars opposite said contacts, said contactor having a flexible connecting strip portion connected between said bars and forming the sole connection therebetween, and spring means mounted between said carriage and said bars and biasing said bars against said support and said contacts, said contactor bars being engageable with all of said contacts simultaneously, said flexible connecting strip portion providing for relative rocking movement between said bars to insure firm contact between said bars and all of said contacts.

References Cited by the Examiner UNITED STATES PATENTS 2,303,693 12/1942 Hill.

2,488,670 11/1949 Koenig 20016 2,589,025 3/1952 Phelps et al.

3,030,459 4/1962 Elliott et al. 2006 3,035,134 5/1962 Hults 200172 3,075,062 1/1963 Iaccarino 200172 3,087,341 4/1963 Hults 7418 3,174,000 3/1965 Golbeck 20016 X KATHLEEN H. CLAFFY, Primary Examiner,

J. R. SCOTT, Assistant Examiner, 

6. IN AN ELECTRICAL SWITCH, THE COMBINATION COMPRISING A HOUSING, AN INSULATING CARRIAGE SLIDABLE LINEARLY IN SAID HOUSING, MEANS FOR MOVING SAID CARRIAGE, AN INSULATING PLATE CONSTITUTING ONE WALL OF SAID HOUSING AND OPPOSITE ONE SIDE OF SAID CARRIAGE, FOUR CONTACTS MOUNTED ON SAID PLATE OPPOSITE SAID CARRIAGE, A CONDUCTIVE CONTACTOR MOUNTED ON SAID CARRIAGE AND HAVING TWO CONTACTOR BARS OPPOSITE SAID CONTACTS, SAID CONTACTOR HAVING A FLEXIBLE CONNECTING STRIP PORTION CONNECTED BETWEEN SAID BARS, AND SPRING MEANS MOUNTED BETWEEN SAID CARRIAGE AND SAID BARS AND BIASING SAID BARS AGAINST AND PLATE AND SAID CONTACTS, SAID CONTACTOR BARS BEING ENGAGEABLE WITH ALL FOUR OF SAID CONTACTS SIMULTANEOUSLY SO AS TO CONNECT THEM ALL TOGETHER, SAID STRIP PORTION FORMING THE SOLE CONNECTION BETWEEN SAID BARS AND PROVIDING FOR RELATIVE ROCKING MOVEMENT THEREBETWEEN TO INSURE FIRM CONTACT BETWEEN SAID BARS AND ALL OF SAID CONTACTS. 